Thanks for the offer! I will hopefully get the PhlatPrinter 3 straightened out (I think I need the heavy duty 10A driver board!) and then I will be able to show a lot of actual physical results i.e. the building of the chassis.

I am quite enamored with velomobiles, and I would love to do an electric assist system in this one:

(click on image for link)

With a rubber (kayak-like) skirt and a little optional roof, these have to be the most efficient road-going vehicle there is. With electric assist (hub motors on the front wheels) and disk brakes, it would be an incredibly efficient daily vehicle that can be used in all weather save when there is deep snow.

The velomobile looks well-designed, and I think an eZee electric motor conversion for the real wheel would work well -- http://ebike.ca/store/store_ezee.php -- and I see that they offer an $1800 Bionx electric conversion kit, too. But the $8000 base price tag makes it impractical. Without a motor, it still has the primary fault commuters find with bikes -- sweating & the need to shower when you get to work. And if the shell is made of fiberglass, that is difficult to get behind -- fiberglass is basically about as toxic as asbestos and lasts forever, the only reason it hasn't been banned yet is that no one has come up with a good replacement.

Going back to your CarBEN EV, I have one basic question -- why such large capacity? I mean, it's great to be thinking about a green big people mover, but isn't the biggest problem the millions of 4-5 passenger sedans in the US, Canada, China, etc that carry just the driver in their daily commute back/forth? I'd love to see what you'd come up with for a small, green 2-person urban commuter vehicle that's super inexpensive.

Never mind... a bit of web searching showed I haven't been paying enough attention to small electric vehicle developments over the past few years. There appear to be quite a few out there -- but again mostly priced higher than for "everyman".

Right, the costs are still in "early adopter" mode. Part of this is the makers are still unsure and going slow, and this begets hesitancy from buyers. It'll get there.

All fair points on the velomobiles. The costs seem high, but if you look at the costs of good bicycles these days, then they might seem more reasonable. I am going to be using yellow Elmers glue on the fiberglass in CarBEN EV5 -- I think this is biodegradable, and the glass is silca/sand so it would return to the earth, too. My concession is the EPS foam core will have to be recycled -- there is a company nearby here in Framingham MA called ReFoamIt that recycles EPS:

Bummer -- I just checked the web site and they cannot accept colored insulation board...

Well, I will look for biodegradable foam that can be used for this, but I have to build the prototype with what I have.

I have a family of four, and the CarBEN EV5 will be under 14 feet long. It's a compact or subcompact car. For 2-3 seats I'd go to a form like Dave Cloud's Dolphin (I'm pretty sure this is earlier in this thread?).

It is no joke -- they destroyed (at least) 3 prototype Apteras: a 2g (gasoline engined), a 2h (serial hybrid), and a sport version of the 2e that had a 150kW motor in it; very fast! They had (apparently) stripped down the chassis before destroying them -- they were finished fully functioning prototypes! The so-called Team B were quite vindictive...

Ironically, the fact that they are now bankrupt might make it possible for the cofounders Steve Fambro and Chris Anthony to restart a company to make uber-efficient electric vehicles.

I've been beavering away on the DataCAD drawing for CarBEN EV5, and these are the 42 sections forward of the high point on the roof; starting at the very front of the nose:

The front sections are ~1" thick because the transition is rapid, and the "stacked" sections are where I need to use a shallower depth to stop a feature. The majority of them will be 1 15/16" thick though -- there are about 85 of these, so this represents less than half -- and they are not done yet. There are five and a half sheets laid out -- I will know how many it will take to do the whole chassis when I finish this!

I will be using 1" thick foam sheets and just cutting two of each. This will let me use the bits I have and the machine will handle them a lot better without any farther futzing with the high current driver board and X-axis stepper motor.

All of the sections have now been smoothed and fleshed out; and then each section has the next section behind it copied overlaying it. This is so there is always an excess of material on all sections, so they can be smoothed just by carving with no filling needed. And the rear doors are laid out flat by cutting a section parallel through them -- they are in a slight angle, so they form a flat V.

I've reached a benchmark on the drafting -- all the sections are drawn in their finished form. The next step will be to drawing the jigsaw joints and lay out the pieces on the 2'x8' foam sheets -- this will take a while!

Here's a more detailed look at a sampling of the section starting just behind the high point of the roof moving back through the CarBEN EV5 chassis.

The different colors show the areas where the adjacent section behind adds material to the forward section. In other words, the tapered shape must have an excess of material -- because both the outside and the inside of the same taper.

I hope this makes sense.

These are the sections at the top hinge of the hatch door. I've started the interlocking lip on the door and the opening that holds the seal and acts as a water gutter when the door is open.

Also, note the 1/2" diameter alignment dowel holes -- these are modeled straight through the entire model. As the chassis tapers, I added other alignment holes.

These sections show the transition in side windows -- the 'C' pillar that is just ahead of the rear wheels. I'm intending the have 2 layers of glazing on the side windows and the hatch and door windows, to provide more insulation.

The section on the right has the front top of the hatch windows, near the center.

The two center rectangles in the floor are the battery bays. The vertical rectangles on the center and right section are for the rear suspension; which is probably going to be a trailing swing arm(s).

These section have the front pieces of the rear wheels and the wheel skirts. Notice the hatch window is getting wider the closer you get the back.

I moved the wheels to where they may fit more efficiently when cutting the foam. And the rear shock / spring units will probably be located here.

The rear wheels are attached to the chassis here, for the purposes of building the model so it can sit on the ground as the car will. After the chassis is (started?) to be fiberglassed, the wheels will be cut out and the suspension components can be designed and have the anchors affixed to the chassis.

The section on the right has voids for where a lateral link arm can be located. This will form a box beam across the floor between the rear wheels.

These sections are at the back of the rear wheels, and I moved them where they fit efficiently on the foam sheets.

I am hoping to be able to use the alignment holes as a wire chase, so I am cutting a connecting channel from the outer hols to the inner holes that pass through the section closer to the back.

These sections show the rear wheel strakes and the diffuser fins on the underside of the chassis. Also, I'm cutting a small area so the tail lights can be wired -- the small triangular holes at the "shoulder".

The rear exhaust air vents (that exit flush to the sides of the rear fenders) are shown in the section on the right.

These sections show the exhaust air vents and the end of the rear wheel strakes. Also, the hatch windows stops at this point.

This is the 'D' pillar and the outer edges of the rear bumper starts on the section on the right.

This is the very back of the chassis (nearly) and the section on the left has the rear door stops and the exhaust air vents. These are 1" thick sections because the taper on the very back is much "steeper".

The center rib on the hatch door will act as a supporting stop at the center of the rear doors. I also have added a small "dorsal" fin at the center of the hatch spine. This was not on the SketchUp model; though I hope to remake the SU model from these sections that is much smoother and much more complete as well with all of the interior voids included in the model.

I cut sections parallel through the rear doors, so these are true size and I'll cut them from the flat foam sheets, avoiding an awkward bit of smoothing. The red lines are the actual edges of the doors and windows, and the gray lines are additional material so I can form the jambs.

The rear bumper and roof "spoiler" trailing edges are a very wide chevron, to match the way the rear doors close.

Here's a couple of views of the stacked sections; mimicking the assembled cut foam pieces.

Please note that the door, wheel skirts, and the hood are separated from the main chassis, just as the foam will be, so they can be assembled separately.

I plan on importing this into SketchUp and smoothing it -- this will make the model much smoother and "tighter" so that hopefully I can then do CFD testing; which should give an approximate Cd (coefficient of drag).

Well, I just finished doing the TV "shoot" for Chronicle at WCVB TV, the local ABC affiliate, and we had a long chat about ecodriving and ecomodding. They probably got plenty of material, with several shots outside the xA, me driving on the local streets, then inside the car for some ecodriving techniques; and also a fair amount on my CarBEN EV5 design: the 3D model and CAD drawings, as well as the three scale models and the full sized pieces.

I'll know more about possible broadcast date, etc. and when I do, I'll post it here. And I have a new blog post about ecodriving:

The chronicle show that I was interviewed for will be shown a week from today -- Thursday June 14th @ 7:30pm. It's on Channel 5 here in the Boston area.

I was interviewed, and I showed my aero-modded Scion xA, I drove it; and I showed my CarBEN EV5 open source design as well. They were here for over two hours, and took probably an hour of video, so most of it won't make it into the show.

****

Quote:

Our show on alternative fuels/hypermiling, etc is slated for next Thursday, the 14th. The show will be posted on our website the following day...but just for ONE DAY. You can bookmark the video link for each segment, though, and you will have access for ever and ever. Feel free to post on websites, and share w family, friends, and Hollywood talent agents.

Okay, the hatch is about halfway smoothed and the opening is better, too. There is a fairly major "pinch" in the 'C' pillar area - I've got more patching to do; which is hard to do until the weather gets warm enough to glue.

I'm finding that hand sanding with a foam block and 120 grit is working well - much more controllable and accurate than the 5" random orbital sander. And when I can afford it I need to buy a couple of new tools (the long flexible sander and an oscillating saw) - and I thin I'll need the Smart ForTwo windshield fairly soon, too.

I will start making some cradle frames out of the 2" foam I bought last spring; so I can turn the car on its sides and upside down.

Hi Neil,out of curiosity, would it make any sense to use a small gas engine, maybe a 0.8 liter engine (or smaller ?) would do it, running at it's most efficient rpm, to run an alternator to charge the batteries (constant rpm, no need for a transmission) ? The Smart Fortwo has a 0.8 L cdi engine that gets around 70mpg (54 HP) and that's with the transmission inefficiencies. This would be an add-on to the other on-board electric generation (regenerative braking, suspension...). Kind of like the Chevy volt but the gas engine only charges the battery (no need for transmission). The battery depletes faster than the charging at high power consumption (high acceleration, highway speed...), but charges more than it used power at low power usage (stopped traffic, low speed...).I know if defeats the purpose of an all-electric vehicle, I'm just curious to hear your thoughts.

For the electric engines, any thoughts about the motor inside the wheel hub ?

If I am right that a ~55kWh battery can go (at least) 300-400 miles on a single charge, then it would probably negate the need for a serial hybrid generator. The FVT eVaro has exactly this type of drivetrain. And that is where I was getting the electric motors and the battery cells that I designed CarBEN EV5 around.

The motors use direct drive via drive shafts only, and this gives virtually the same efficiency as hub motors, while gaining a big advantage of minimizing unsprung weight. In fact, the eVaro motors have the dick brakes *inboard* right next to the motor on the drive shaft, so the unsprung weight is even lower than normal.

+++++++++

I am going to bring my CarBEN EV project to the Framingham (MA) Earth Day Festival, which is happening on April 27th 11:00am-3:00pm at the Framingham Center Common; between Vernon Street, Edgell Road and Route 30; just north of the Framingham Center exit on Route 9.

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